Tunneling Characteristics and Low Frequency Noise of High-Tc Superconductor/Noble-Metal Junctions

Published

March 22, 2004

Author(s)

Yizi Xu, John (Jack) W. Ekin

Abstract

We report extensive measurements of transport characteristics and low-frequency resistance noise of c-axis YBCO/Au junctions. The dominant conduction mechanism is tunneling at low temperatures. The conductance characteristic is asymmetric, and the conductance minimum occurs at a non-zero voltage. These features can be qualitatively explained by modeling by YBCO/Au interface with a Schottky barrier. The model shows the YBCO surface behaves like a p-type semiconductor, with a Fermi degeneracy of about 0.1 eV. This is consistent with a carrier density of 3 x 10 ²¹ cm^-3, and a band mass of 2.6 times that of the free-electron mass. The barrier-height is approximately 1.0 eV. We show that interface states and disorder play an important role in determining the conductance characteristics. Low-frequency noise measurements of many junctions with contact areas ranging from 4 υm² to 64 υm², over a wide temperature and bias range, indicate that the noise figure for engineering design may be expressed as a normalized resistance fluctuation δR/Rapproximately equal}6×10^-4/√Hz at 10 Hz.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Volume

69

Pub Type

Journals

Keywords

1/f noise, charge-trapping, defects, disorder, high-temperature superconductors, interface states, low-frequency noise, Schottky-barrier, semiconductor/metal contacts

Citation

Xu, Y. and Ekin, J. (2004), Tunneling Characteristics and Low Frequency Noise of High-Tc Superconductor/Noble-Metal Junctions, Physical Review B (Condensed Matter and Materials Physics) (Accessed October 18, 2025)